ive just bought Corsair HX620 from overclockers & for the first hour it is on it makes a nasty buzzing noise, not dead loud but annoying all the same,
is anyone else having the same problem?

Nope can't say mine does. Give it a couple of days to 'bed in' and if you don't get an improvement I would RMA it.
 
It was a good choice of PSU you may have just been unlucky.

Mine doesnt do anything like that either, so there might be something afoot. Well enjoy OCUK RMA, it sucks in my experience.

Oh no!
 
It's not normal. I can't hear my PSU at all over my stupid stock CPU fan. (a temporary situation, I assure you!) How close are you when you hear the buzzing?

That's a first.
 

 
tower is on my desk, my head is 2 foot away max  

someone say this ain't so. im about to get one next week, and having high hopes of its quality... *wishing*

if you read on corsair forums, the ram guy claims the only noise coming from this PSU is airflow from the fan, any other noises & they will swap it for you. just debating whether to RMA mine

Like I said. Give it a couple of days and if it doesn't stop making a noise RMA it.
 
I had a Hyper PSU that when it was brand new clicked a lot. Then after a day it was fine and has been trouble free since.

I have 2 HX620's and when I had my first one, after a week it started making alot of noise. And I did,nt know what it was, after taking a closer look I found that the sticker that was on the fan came lose and was stuck inside the psu and kept hitting the fan. So I just got it out of the psu and it was quite again. I took the sticker out of the second psu before I even installed it.

We will replace it or you can go back thru your retailer. Also, did you peek into the PSU to see if there was some object stuck in there? Our first batch had that problem mentioned here with the stickers peeling but we resolved that, better glue    
 
Let me know if I can assist you in any way.  

I noticed just this week that my HX520 starts to make some noise after starting from Hibernation.  First time I was getting ready to check out the sound but it stopped before I could open the case.  The second time I was able to open it and check all of my other fans first...expected it to be either a case or slot fan instead.  Then I realized it was the Corsair PSU...I will check later for a piece of paper...hopefully that is it as the fan is super quiet.
Tim